JP4568642B2 - Optical scanning device and image forming apparatus - Google Patents

Description

The present invention relates color laser printer, a digital color copying machine, the optical scanning device and image forming equipment used in facsimile.

In recent years, color digital copying machines, color laser printers, etc. have a plurality of stations for increasing the recording speed, and form images of different colors on a plurality of scanned surfaces, and sequentially transfer these images onto a transfer medium. As a result, so-called tandem color image forming apparatuses that form color images have become widely known.
Also in the tandem type color image forming apparatus, an optical scanning apparatus has been proposed in which a scanning optical system is arranged on the left and right with a single deflector interposed therebetween to perform optical scanning on four photosensitive members (for example, Patent Document 1). reference.).
On the other hand, the beam spot diameter has been reduced along with the improvement in the quality of color images. The smaller the beam spot diameter, the narrower the depth and the smaller the allowable amount of beam waist position deviation. Therefore, in order to adjust the beam waist position particularly in the sub-scanning direction, a linear image optical system, for example, a cylindrical lens is used as a light source. A beam waist position shift due to a surface accuracy error of a scanning lens is adjusted by adjusting in the axial direction.

In addition, a scanning lens made of an aspherical surface is being advanced to reduce the beam spot diameter, and a resin-made scanning lens is becoming the mainstream for reducing the cost of the scanning lens. As an advantage of producing by molding resin, a plurality of molds can be obtained, which is advantageous for cost reduction.
However, in the case of taking a plurality, the surface accuracy of the scanning lens of each cavity is not necessarily constant due to the accuracy of the metal piece for creating the mirror surface, the temperature distribution of the mold, and the like.
Therefore, in the case of the optical scanning device used in the tandem type image forming apparatus, there is a problem that the adjustment of the cylindrical lens has to be performed for each station, which requires adjustment time and increases the cost. In an example of a mechanism, adjustment of the cylindrical lens takes 15 to 30 seconds per station. Since every station takes about the same time, the time required for adjustment was approximately 1 to 2 minutes.

JP 2002-90672 A

  The present invention configures a scanning optical system in the adjustment of the optical axis direction of a line image optical system in an optical scanning device including a plurality of scanning optical systems used in a tandem type color image forming apparatus and the like By selecting the same type of scanning lens from the same cavity, the adjustment amount in the optical axis direction of the line image optical system is made substantially the same at each station, thereby shortening the adjustment process time on the assembly line. The purpose is to make it easier.

According to the first aspect of the present invention, there are a plurality of stations corresponding to a plurality of development colors, and each station has at least one light source, a coupling lens, and a light beam from the light source that is long in the main scanning direction. A linear image optical system that converts the light beam from the linear image optical system into the main scanning direction, and the plurality of light beams deflected by the deflecting means on a corresponding scanned surface. A scanning optical system composed of a plurality of optical elements to be guided, and at least one of the plurality of optical elements includes a scanning lens made of resin with a plurality of molds. The functionally corresponding resin-made scanning lens is taken out from the same cavity in the mold, and the line image light in the traveling direction of the light beam passing through the line image optical system. Have a linear image optical system adjusting mechanism for advancing and retracting the system for each of the plurality of stations, integrally holding the plurality of the lines forming optical system provided in each station the line image optical system adjusting mechanism holding member And a holding member adjustment mechanism that allows the position of the linear image optical system provided for each of the plurality of stations to be adjusted integrally by moving the holding member straight forward and backward in the direction of the deflecting unit. It is characterized by.
According to a second aspect of the present invention, in the optical scanning device according to the first aspect, the holding member adjusting mechanism is provided for each of the plurality of stations by causing the holding member to move straight forward and backward in the direction of the deflecting unit. It is a mechanism for integrally adjusting the position of the line image optical system, and the line image optical system adjustment mechanism is a mechanism for finely adjusting the position of each line image optical system .

In the invention described in claim 3, in the optical scanning apparatus according to claim 1 or 2, wherein the linear image optical system adjusting mechanism or the holding member adjusting mechanism is characterized by a cam mechanism der Rukoto.
The invention according to claim 4, in the optical scanning apparatus according to claim 1 or 2, wherein the linear image optical system adjusting mechanism or the holding member adjusting mechanism is characterized by a rack-pinion mechanism der Rukoto.
According to a fifth aspect of the present invention, there is provided an image forming apparatus using the optical scanning device according to any one of the first to fourth aspects .

According to the present invention, the adjustment time for moving the cylindrical lens in the direction of the deflector in order to adjust the beam waist to the surface to be scanned can be shortened.
Since the resin-made scanning lens is provided with an identification symbol, it is possible to eliminate an error during assembly.

FIG. 1 is a schematic diagram showing an image forming apparatus to which the present invention is applied. The figure (a) is a top view, The figure (b) is a side view.
In the figure, reference numeral 1 is a light source, 2 is a coupling lens, 3 is a cylindrical lens as a line image optical system, 4 is an optical deflector, 5 is a first scanning lens, 6 is a second scanning lens, and 7 is a covered lens. A scanning plane, S, indicates a station.
A light beam emitted from a light source 1 composed of an LD array or the like is coupled into a substantially parallel light beam by a coupling lens 2 and is incident on a cylindrical lens 3 whose bus line direction is aligned with the main scanning direction, and is elongated substantially in the main scanning direction. The light is incident on the optical deflector 4 while condensing in a shape. The light beam deflected by the optical deflector 4 passes through the first scanning lens 5 made of resin and the second scanning lens 6 made of resin, and forms an image on a scanned surface 7 such as a photosensitive member. The semiconductor laser and the light source 1 are arranged on the optical axis of the coupling lens 2, and the light beam travels along the optical axis with the optical axis as the center.
As described above, each station of S1 to S4, for example, a scanning optical system corresponding to four colors of Bk (black), C (cyan), M (magenta), and Y (yellow) is applied to a scanning surface corresponding to each color. An image is formed to form a color image.
The deflecting surface of the optical deflector 4 may be a common deflecting surface, or may be composed of two upper and lower deflecting surfaces as shown in FIG.
Although the example of the cylindrical lens has been described as the line image optical system, the same object can be achieved by a cylindrical concave mirror, a hologram, or the like. In addition, a so-called anamorphic lens type having optical power in both the main scanning direction and the sub-scanning direction can be used as the line image optical system. In the case of a hologram or anamorphic lens type, the above adjustment is possible just by moving the lens itself straight, just like a cylindrical lens, but in the case of a cylindrical concave mirror, only the concave mirror is moved by fixing the light source. Then, since the diameter of the light beam reflected by the concave mirror changes, only in this case, the concave mirror is moved integrally with the light source. However, in the following description, the cylindrical lens is linearly advanced and retracted as a representative of the line image optical system, but includes that in which the concave mirror and the light source are integrated and moved.

The optical scanning apparatus shown in FIG. 4 includes four sets of scanning optical systems, and four first scanning lenses 5 and four second scanning lenses 6 are used.
Here, for example, it is assumed that the first scanning lens 5 made of resin and the second scanning lens 6 made of resin are each formed by molding four pieces, and the first scanning lens 5 and the second scanning lens 6 are each randomly selected. When combined with the cavities, the four sets of scanning optical systems have different optical characteristics, and the adjustment amount of the cylindrical lens is usually different for the four groups, so that adjustment time is required.
In the present invention, the same type of scanning lens used in the optical scanning device, for example, if the first scanning lens 5 is used, the first scanning lens 5 is composed of four of the same cavity, and the second scanning lens 6 is also the same cavity. By comprising four, the four sets of scanning optical systems have substantially the same optical characteristics. Of course, the optical characteristics of the four sets of scanning optical systems do not become exactly the same due to surface accuracy errors of optical elements other than the scanning lens, for example, the folding mirror, but as a factor of beam waist position deviation in the sub-scanning direction in particular, Since the surface accuracy error of the scanning lens is dominant, it may be regarded as substantially the same. Therefore, if one of the four sets of cylindrical lenses is adjusted and the adjustment amount is derived, the adjustment time is approximately 4 minutes by arranging the other three sets at positions based on the adjustment amount. 1

For example, in the black station of the first station S1, the cavity NO. 1 is used, the first scanning lens 5 is cavity NO. 1 and the second scanning lens 6 has a cavity NO. 3 is used, the second scanning lens 6 is cavity NO. By adjusting the cavity of the first scanning lens 5 and the cavity of the second scanning lens 6 in the optical scanning device as in the case of using 3, the adjustment time in the optical axis direction of the cylindrical lens can be shortened. it can.
As an adjustment procedure, an adjustment in the optical axis direction of the cylindrical lens 3 of one station is performed, and the adjustment amount is first applied to the cylindrical lenses 3 of all other stations. At this point, the beam waist positions of the sub-scans of all the stations are adjusted almost on the surface to be scanned. However, when adjusting with higher accuracy, the sub-scanning beam waist positions are adjusted with fine adjustment from the position where the cylindrical lens 3 is arranged. Although the scanning beam waist position can be adjusted, the adjustment time can be shortened as compared with the case where the cavities of the scanning lenses of each station are randomly combined.

This is made possible by the fact that the variation between shots in each cavity is extremely small compared to the difference between the cavities in the shape accuracy (surface accuracy) of the scanning lens.
Of course, it is possible to increase the accuracy by repeating the metal piece processing and reduce the difference between the cavities, but it is difficult because the metal piece processing takes time and cost.
In the above description, both scanning lenses are made of resin lenses. However, even if one of the lenses is made of glass, at least one of the scanning lenses is made of a resin lens. The present invention can be applied to the case where it is manufactured by mold forming.

In practicing the present invention, a unique symbol indicating that the cavity is used, such as a cavity number, may be attached to a position not used as the optical surface of the metal piece of each cavity. The place to be given should be a place where the symbol can be read from the outside even after assembly. By doing so, it is less likely that lenses from different cavities will be mistaken, and even if an error occurs, it can be confirmed later.
According to the present invention, the beam waist on all the scanning surfaces is adjusted to the best position, so that a stable beam spot diameter can be achieved, and the shape accuracy of the scanning lens, particularly the accuracy in the sub-scanning direction, can be toleranced. As a result, the yield can be improved and the cost can be reduced.

FIG. 2 is a schematic view showing another image forming apparatus to which the present invention is applied.
This configuration shows an example in which the light source is configured as a multi-beam. In this configuration, a plurality of light beams share the cylindrical lens 3. Therefore, the light beams from the individual light sources do not enter the cylindrical lens 3 perpendicularly, but enter each with a slight angle. Normally, the absolute value of the tilt is reduced by tilting the cylindrical lens 3 in the opposite directions with respect to the optical axis. However, since the angle is small, the optical performance is not adversely affected.
Even in this configuration, the adjustment of the beam waist on the scanned surface 7 can be performed by adjusting the cylindrical lens 3 in the optical axis direction.
In general, in the case of a normal lens, when moving in the optical axis direction, it is not possible to shift in a direction orthogonal to the optical axis, but in the case of a cylindrical lens, it is moved in a direction having no optical power (bus line direction). There is no problem even if you let them. That is, no optical problem occurs even if movement occurs in the direction perpendicular to the optical axis and in the direction parallel to the paper surface in FIG.
Therefore, if the cylindrical lens 3 is moved straight without changing the angle with respect to the optical axis, the light beam passage position slightly moves in the direction of the generatrix, but the optical performance does not change. Adjustment is possible. In addition, since each light beam from a plurality of light sources is generally adjusted to a parallel light beam before entering the cylindrical lens 3, there is no difference in the position of the beam waist due to the difference in the light source.

FIG. 3 is a view showing an example of a beam waist adjusting mechanism. The figure (a) is a top view, The figure (b) is a XX arrow directional view.
In the figure, reference numeral 10 is a lens holder, 11 is an eccentric cam, 12 is a rotating member, 13 is a leaf spring, 14 is a guide pin, 15 is a guide groove, A is a lens moving direction, AC is a cam rotating direction, and B is The substrate, C is a cam mechanism, P is an index, and SC is a scale.
When a cylindrical concave mirror is used as the line image optical system, it is assumed that a light source is also fixedly mounted on the lens holder 10.
The adjustment method will be described below.
First, the case where all the cylindrical lenses 3 are configured to be independently adjustable will be described. The adjustment process includes rough adjustment and fine adjustment. In some systems, the same adjustment mechanism is used for both, and in other cases, the adjustment mechanisms of the both are configured separately. Usually, the same mechanism is used for both coarse adjustment and fine adjustment because of the manufacturing cost. Since there is almost no change in the procedure of work in any configuration, it will be described here as a dual-use type.

For example, the cam mechanism C is used as the adjustment mechanism, and the rotating member 12 fixed to the eccentric cam 11 is inserted into the slit portion of the rotating member 12 with, for example, a minus driver, and rotated clockwise as shown by an arrow AC or counterclockwise. By rotating clockwise, the cylindrical lens 3 adhered to the lens holder 10 by dropping, for example, is caused to advance straight (retreat) in the optical axis direction as indicated by an arrow A. The rotation angle of the eccentric cam 11 can be confirmed by the relative position of the index P prepared on the cam side and the scale SC marked on the lens holder around the cam. The reference position is clearly indicated on the scale SC, and the cylindrical lens 3 is arranged at the designed position by matching the index P of the eccentric cam 11 with the reference position of the scale SC at the manufacturing stage. Since the index P and the scale SC are for viewing relative positions, the scale may be provided on the cam side.
A leaf spring 13 is fitted between the back surface of the eccentric cam 11 and a part of the lens holder 10, and the lower surface of the lens holder 10 is always pressed against the upper surface of the substrate B so that stable movement is possible. Three guide pins 14 are implanted on the lower surface of the lens holder, and each guide pin 14 is fitted into a guide groove 15 provided on the substrate B to ensure smooth straight travel.
Such an adjustment mechanism is provided corresponding to all the cylindrical lenses 3.

An optical system other than the photoconductor is assembled and attached to the adjustment jig, and a beam spot on the surface to be scanned corresponding to the photoconductor surface is examined. For example, with respect to the station 1, the cylindrical lens 3 is moved in the optical axis direction by rotating the cam so that the beam spot is minimized. At this time, it is generally unclear whether the initial rotation direction of the cam is clockwise or counterclockwise. Therefore, the direction is determined by trial and error and takes a little time. After the adjustment, the station is fixed in position by a screwing mechanism or the like (not shown). Then, the rotation angle of the cam at that time is read from the scale, and the cams of other stations (for example, station 2) are unconditionally rotated to that angle. By this rotation, the beam waist of the station should basically coincide with the surface to be scanned. After that, fine adjustment may be performed while checking the beam spot for each station. The time required for fine adjustment by this method can be much shorter than the time required for coarse adjustment. Rather than simply turning the cams of other stations unconditionally, if you rotate the beam spot to a certain angle while observing the beam spot, you can continue to rotate the beam spot to minimize it, or vice versa Since it can be seen that it should be returned, the adjustment time is further shortened. Each station is also positioned and fixed by a mechanism (not shown) after adjustment.
If the scanning lens used in the other station is selected from a different cavity than that of the first station, the cam rotation angle cannot be determined unconditionally and must be repeated from the first trial and error. In the worst case, 4 coarse adjustments and 4 fine adjustments are necessary, and it is clear that the adjustment time is prolonged. On the other hand, according to this adjustment method, rough adjustment is performed once, angle adjustment is performed 3 times, and fine adjustment is performed 4 times. According to this method, the time required for adjustment is approximately one-half or less of the conventional time.

FIG. 4 is a diagram showing an example of another adjustment mechanism.
In the figure, reference numeral 16 denotes a rack, 17 denotes a pinion, and AP denotes a rotation direction of the pinion. Other reference numerals apply to those shown in FIG. In FIG. 4, guide pins and guide grooves are omitted. When the concave reflecting mirror described above is used as the line image optical system, the light source is also integrated on the substrate B.
This figure shows an example in which the present invention is applied to the multi-beam system shown in FIG. 2, and only the first station S1 and the second station S2 are shown in order to avoid complexity. The third and fourth stations (S3, S4) (not shown) have basically the same configuration.
As described above, in the case of the cylindrical lens, there is no problem even if the light beam is moved in the generatrix direction. That is, no optical problem occurs even if movement occurs in the direction perpendicular to the optical axis and in the direction parallel to the paper surface in FIG. However, in the case of the anamorphic lens type, the aberration increases when the direction of the light beam is too far away from the optical axis. Therefore, it is preferable to arrange a plurality of light sources of multi beams as small as possible.
This adjustment mechanism moves the substrates B1 to B2 (to B4) straight by the combination of the rack 16 and the pinion. The pinion 17 may be provided with an index P so that the relative rotational position can be read in relation to a scale provided on a surrounding fixed portion (not shown).
Although the rotation method of the pinion 17 is not particularly specified, the pinion 17 may be provided in the same manner as the slit portion of the rotation member 12 shown in FIG. Or you may form the white part of the parameter | index P in a recessed part, and it may serve as a slit part. In some cases, the pinion itself may be directly rotated. The substrate B1 is linearly moved in the direction of the arrow A1 in combination with the action of a guide focus guide groove (not shown) by the force by which the rack is moved by the rotation of the pinion.
The effect of shortening the adjustment time by this method is almost the same as that of the configuration shown in FIG.
In the case of multi-beams, especially in the case of two light beams, it is more effective to prevent the light beams from being kicked by moving the crossing angle of the two light beams in the same direction rather than moving along one light beam.
Needless to say, this configuration can also be applied to the single beam shown in FIG.

FIG. 5 is a diagram showing still another example of the adjustment mechanism.
In the figure, the reference numerals shown in FIG. 3 apply mutatis mutandis. In FIG. 5, guide pins and guide grooves are omitted.
Other adjustment methods will be described below.
As described above, in the case of a cylindrical lens, no optical problem occurs even if the light beam is moved in the direction of the generatrix.
Therefore, for example, it is considered that a plurality of cylindrical lenses 3 are integrated so that the whole is linearly moved toward and away from the deflector 4. Since each cylindrical lens 3 does not change its direction even if it moves, the target function is not impaired. However, if the distance is extremely close or too far, the effective range of the cylindrical lens 3 is off the optical axis. However, if the movement is a practical range of several millimeters, the effective light beam from the coupling lens 2 is cylindrical. There will be no kick at the end of the lens 3.

In this adjustment method, the substrate B portions of the plurality of cylindrical lenses 3 formed integrally in this way are moved straight by, for example, the cam mechanism C1 to perform coarse adjustment and fine adjustment of a specific station (for example, station 1). Do. In this way, when the adjustment of the station is completed, the coarse adjustment of the other stations is completed. The position of the substrate B is fixed to the main body with a screw or the like (not shown).
The cylindrical lenses 3 of the other stations are placed on the substrates B2 to B4 individually prepared on the moving substrate B together with the fine adjustment mechanisms C2 to C4. For fine adjustment of each station, cam mechanisms C2 to C4 are used, and fine adjustment as indicated by arrows A2 to A4 is performed individually. Since the fine adjustment mechanisms C2 to C4 require a small amount of movement, they can be made compact. Of course, each adjustment is fixed.
In the drawing, cam mechanisms C2 to C4 are used as fine adjustment mechanisms, but mechanisms other than the cam mechanism may be used. According to this method, all the adjustments are completed by one coarse adjustment and four fine adjustments, which is less than one third of the conventional adjustment time, and the adjustment time is greatly reduced.

FIG. 6 is a partial view showing another example of the adjusting mechanism.
In the same figure, the code | symbol G shows the guide groove provided in the fixed board | substrate. Although only the station 1 and the station 2 are shown in the figure, the other stations are substantially the same, and the illustration is omitted.
In the case of the anamorphic lens type, it is preferable that the optical axis does not shift. Therefore, a guide for moving each line image optical system in the optical axis direction is provided, and when the substrate B1 moves straight, each moves in the optical axis direction. You can do it.
In the figure, guide grooves G1 and G2 are provided on the fixed substrate side (not shown) in the optical axis direction of each line image optical system, and the line image optical system 3 of the first station S1 is a long hole provided in the substrate B1. It is configured to be movable in the direction of the guide groove by a guide pin (not shown) provided in the lower part. Similarly, the substrate B2 of the second station S2 is configured to be movable in the guide groove direction by a guide pin (not shown) provided in the lower portion through a long hole provided in the substrate B1. The long hole through which the guide pin of each moving part passes is oriented in a direction orthogonal to the moving direction indicated by arrow A1, and the guide pin is configured to be slidable along the long hole. With this configuration, when the substrate B1 moves straight in the direction indicated by the arrow A1, that is, in the vertical direction in the figure, the respective moving image parts are shifted by the guide pins and the guide grooves G while the respective moving parts are slightly shifted in the horizontal direction in the figure. It moves in the direction of each optical axis.
According to this configuration, the line image optical system can be moved without causing an optical axis shift, and therefore can be applied to an optical system having optical power in both the main scanning direction and the sub-scanning direction.

FIG. 7 is a view showing still another image forming apparatus to which the present invention can be applied.
In the figure, reference numerals 21 to 24 are optical scanning devices, 31 to 34 are scanned surfaces, 41 to 44 are developing devices, 51 to 55 are exposure light beams, 62 is an external mechanism, 63 is a printer controller, and 70 is an image forming apparatus main body. Respectively.
Even when the optical scanning device (station) is configured independently for each development color as in this device, the basic components such as the scanning lens are the same as each other. By using a lens taken out from the same cavity as the scanning lens used in each station, the beam waist adjustment time can be shortened.

1 is a schematic diagram illustrating an image forming apparatus to which the present invention is applied. It is a schematic diagram which shows the other image forming apparatus to which this invention is applied. It is a figure which shows an example of a beam waist adjustment mechanism. It is a figure which shows the example of another adjustment mechanism. It is a figure which shows the example of another adjustment mechanism. It is a fragmentary figure which shows the example of another adjustment mechanism. It is a figure which shows the further another image forming apparatus which can apply this invention.

Explanation of symbols

1 Light source (semiconductor laser, LD array, etc.)
2 Coupling lens 3 Cylindrical lens 4 Polygon mirror 5 First scanning lens 6 Second scanning lens 7 Photosensitive surface (scanned surface)
DESCRIPTION OF SYMBOLS 10 Lens holder 11 Eccentric cam 12 Rotating member 14 Guide pin 16 Rack 17 Pinion

Claims (5)

A plurality of stations corresponding to a plurality of development colors, each station having at least one light source, a coupling lens, and line image optics for converting a light beam from the light source into a linear light beam that is long in the main scanning direction Scanning optical system comprising: a system; deflection means for deflecting a light beam from the line image optical system in the main scanning direction; and a plurality of optical elements for guiding the plurality of light beams deflected by the deflection means to a corresponding surface to be scanned An optical scanning device using a resin scanning lens with a plurality of molds, wherein at least one of the plurality of optical elements includes:
The resin scanning lenses functionally corresponding to each station are taken out of the same cavity in the mold,
The traveling direction of the light beam passing through the beam forming optical system, have a linear image optical system adjusting mechanism for advancing and retracting the wire forming optical system for each of the plurality of stations,
A holding member that integrally holds the linear image optical system and the linear image optical system adjustment mechanism provided for each of the plurality of stations, and the holding member is moved forward and backward in the direction of the deflection unit to an optical scanning device, characterized in that it comprises a holding member adjusting mechanism to integrally adjustable positions of the line image optical system provided for each of a plurality of stations. 2. The optical scanning device according to claim 1, wherein the holding member adjusting mechanism moves the holding member linearly in the direction of the deflecting unit to position the line image optical system provided for each of the plurality of stations. An optical scanning device characterized in that the line image optical system adjustment mechanism is a mechanism for finely adjusting the position of each line image optical system .   3. The optical scanning device according to claim 1, wherein the linear image optical system adjustment mechanism or the holding member adjustment mechanism is a cam mechanism.   3. The optical scanning device according to claim 1, wherein the linear image optical system adjustment mechanism or the holding member adjustment mechanism is a rack and pinion mechanism.   An image forming apparatus using the optical scanning device according to claim 1.

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